fix: update upper bound for signed integers in min and max folding

[tserg]

What I did

Fix #3284.

How I did it

Update the bound to int256, which is >= 2 ** 255.

How to verify it

See tests.

Commit message

fix: update upper bound for signed integers in `min` and `max` folding

Description for the changelog

Update upper bound for signed integers in min and max folding

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[codecov-commenter]

Codecov Report

Merging #3288 (a6013db) into master (d320b80) will increase coverage by 0.06%.
The diff coverage is 85.71%.

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@@            Coverage Diff             @@
##           master    #3288      +/-   ##
==========================================
+ Coverage   88.86%   88.92%   +0.06%     
==========================================
  Files          84       84              
  Lines       10597    10605       +8     
  Branches     2213     2215       +2     
==========================================
+ Hits         9417     9431      +14     
+ Misses        770      768       -2     
+ Partials      410      406       -4     

Impacted Files	Coverage Δ
vyper/builtins/functions.py	90.73% <80.00%> (+0.30%)	⬆️
vyper/semantics/analysis/local.py	91.36% <100.00%> (+0.05%)	⬆️
vyper/codegen/core.py	86.74% <0.00%> (+0.04%)	⬆️
vyper/semantics/analysis/module.py	86.29% <0.00%> (+0.06%)	⬆️
vyper/ast/nodes.py	94.10% <0.00%> (+0.31%)	⬆️
vyper/ast/folding.py	93.27% <0.00%> (+0.53%)	⬆️

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[charles-cooper]

this fails for a different reason, no?

[tserg]

It fails on the same branch:

vyper/vyper/builtins/functions.py

Lines 2019 to 2020 in efb0032

	if isinstance(left, int) and (min(left, right) < 0 and max(left, right) >= 2 ** 255):
	raise TypeMismatch("Cannot perform action between dislike numeric types", node)

Although max_value(int256) + 1 is out of bounds, it is currently not type-checked before folding so it is not flagged as an error. Therefore, this slightly modified example would also compile:

@external
def foo():
    a: int248 = min(1, max_value(int248) + 1)

[charles-cooper]

the example is a bit confusing tbh because the operands are not really valid to begin with. and i'm realizing the fix itself does not block examples which are in the int255 range but do not typecheck, like:

min( min_value(int16)/*type: int16*/, max_value(int8)/*type: int8*/)

can we use get_common_types here like other builtins which deal with numeric literals? i think that can fix the typechecking issue.

[charles-cooper]

i guess, if/when we move constant folding after typechecking this will be moot and we can remove the checks inside of the evalute implementations

[tserg]

the example is a bit confusing tbh because the operands are not really valid to begin with.

I have moved this test to #3201 instead. I think that PR is more relevant for addressing these cases.